Hydrosilylation method and process for producing curing agent making use of the same

ABSTRACT

This invention provides a hydrosilylation method in which hydrosilyl groups are added to olefin using a metal catalyst, which comprises controlling the hydrosilylation reaction by allowing a compound selected from thiazoles and phosphines to coexist in the reaction system, and a process making use thereof for the production of a hydrosilyl group-containing organic curing agent. This invention gives a method for easy control of hydrosilylation reaction and a process making use thereof for the production of an organic compound modifying silicon compound having 2 or more hydrosilyl groups in the molecule. This compound is used as a curing agent of addition type curable compositions. As an accompanying effect, storage stability of the produced curing agent is improved when a catalyst and additives of this invention remain therein, in comparison with the case in which only the catalyst remains.

TECHNICAL FIELD

This invention relates to a hydrosilylation method and a process for theproduction of an organic curing agent containing hydrosilyl groups.

BACKGROUND ART

Hydrosilylation reaction in which hydrosilyl group is added to olefin isbroadly known as a method for the production of organic siliconcompounds and used in various applications. As an example of suchapplications, various hydrosilyl group-containing organic curing agentshave been developed as curable liquid compositions having excellent deepcurability, in order to produce rubber-like substances throughcross-linking and curing of polymers by hydrosilylation reaction.

Illustratively, an agent, in which a polyorganosiloxane having 2 or morein average of vinyl groups on terminals or in molecular chain of onemolecule is cross-linked with a polyorganohydrogensiloxane having, in 1molecule, 2 or more hydrogen atoms binding to the silicon atom, has beendeveloped and used as sealing materials and potting materials making useof its excellent weather resistance, water resistance and heatresistance.

In addition, as disclosed in JP-A-3-95266 (the term "JP-A" as usedherein refers to a "published unexamined Japanese patent application"),an organic curing agent has recently been developed which contains atleast 2 hydrosilyl groups (not a polymer) in its molecule instead of thepolyorganohydrogensiloxane usually used in curing reaction byhydrosilylation. According to the disclosure, this organic curing agentgenerally has good compatibility with alkenyl group-containing organicpolymers.

In consequence, it has been found that, when the aforementioned alkenylgroup-containing organic polymer is cured with the aforementionedorganic curing agent which contains at least 2 hydrosilyl groups in itsmolecule using a hydrosilylation catalyst, excellent characteristics canbe obtained as follows;

(1) since the aforementioned curable composition is a homogeneoussystem, quickly curable and excellent in deep curability, a curedproduct having excellent mechanical characteristics such as sufficienttensile characteristics and the like can be obtained from the curablecomposition,

(2) since alkenyl group-containing organic polymers having any type ofbackbone skeleton can be used, curing agents applicable to markedlybroad range of use can be produced, and

(3) since the aforementioned organic curing agent which is not a polymergenerally has low viscosity, it is advantageous from the viewpoint ofworkability for the production of cured products.

Hydrosilylation reaction is used also in the production of such anorganic curing agent.

In general, when the hydrosilylation reaction is carried out to effectaddition of hydrosilyl groups to olefin, various transition metalcomplexes such as of cobalt, rhodium, nickel, palladium, platinum andthe like are used as catalysts. In that case, it is necessary to excludecatalyst poisons from the reaction system as many as possible. Forexample, Nielsen discloses various interfering substances and inhibitingsubstances in U.S. Pat. No. 3,383,356, and Ashby discloses ahydrosilylation catalyst which shows a higher activity than those ofconventional catalysts due to the absence of interfering impurities inJP-A-60-54734.

On the other hand, various compounds are known as storage stabilityimparting agents for curable compositions of hydrosilylationcross-linking system. Examples of such compounds include an ethylenic oraromatic unsaturated amide (U.S. Pat. No. 4,337,332), an acethyleniccompound (U.S. Pat. No. 3,445,420), an ethylenic unsaturated isocyanate(U.S. Pat. No. 3,882,083), an olefinic siloxane (U.S. Pat. No.3,989,667), conjugate ene-ynes (U.S. Pat. No. 4,465,818), an unsaturatedhydrocarbon diester inhibitor (U.S. Pat. No. 4,256,870), abis-hydrocarbonoxyalkyl maleate inhibitor (U.S. Pat. No. 42562096) andthe like. These storage stability imparting agents, however, are aimedat inhibiting catalytic activities at around room temperature but notreducing catalytic activities at the time of heating.

Since hydrosilylation catalysts activate silicon-hydrogen bonding at thetime of hydrosilylation, they also cause side reactions. That is, sidereactions such as hydrolysis of hydrosilyl groups, disproportionationand polymerization of polysiloxane and the like are generated.

When hydrosilyl groups are allowed to remain in product molecules,reduction of the number of remaining hydrosilyl groups caused by theseside reactions becomes a great problem. Also, similar side reactionsprogress gradually during storage of the formed material aftercompletion of the reaction and deteriorate its storage stability in somecases.

In addition, since the hydrosilylation reaction is exothermic,generation of an abrupt reaction may cause dangers such as suddentemperature increase and bumping in the reaction system. In general, thecatalyst may be used in an irreducibly minimal amount in order to avoidsuch dangers, but, in that case, another problems such as unexpectedinactivation of the catalyst and the like are apt to occur.

The object of the present invention is to provide a means for theproduction of a curing agent for a stabilized curable composition ofhydrosilylation cross-linking system, making use of a hydrosilylationreaction in which hydrosilyl groups are added to olefin using a metalcatalyst, wherein the hydrosilylation reaction is controlled to preventthe aforementioned side reactions.

DISCLOSURE OF THE INVENTION

Taking the aforementioned problems involved in the prior art intoconsideration, the inventors of the present invention have conductedintensive studies and found that control of the hydrosilylation reactioncan be achieved through appropriate repression of the catalytic activityby positively adding a catalyst poison to the reaction system, and havethereby accomplished the present invention.

The above object can be achieved by the hydrosilylation method of thepresent invention and a process for the production of a curing agentmaking use thereof.

Accordingly, the present invention comprises the following construction.

1. A hydrosilylation method in which hydrosilyl groups are added toolefin using a metal catalyst, which comprises controlling thehydrosilylation reaction by allowing a compound selected from thiazolesand phosphines to coexist in the reaction system.

2. The hydrosilylation method according to the above item 1, wherein thecompound selected from thiazoles and phosphines is benzothiazole.

3. The hydrosilylation method according to the above item 1, wherein thecompound selected from thiazoles and phosphines is triphenylphosphirie.

4. The hydrosilylation method according to any one of the above items 1to 3, wherein the metal catalyst is a platinum catalyst.

5. A hydrosilylation method which comprises carrying out hydrosilylationin accordance with the method of any one of the above items 1 to 4 undersuch conditions that hydrosilyl groups are present in excess of thenumber of olefin carbon-carbon double bonds.

6. A process for producing an organic curing agent containing hydrosilylgroups, which comprises carrying out hydrosilylation of olefin and apolyvalent hydrogen organosilicon compound using the method of the aboveitem 1, under the conditions of the method of the above item 5 so thathydrosilyl groups remain in the formed material after the reaction.

7. The process for producing an organic curing agent containinghydrosilyl groups according to the above item 6, wherein the compoundselected from thiazoles and phosphines is benzothiazole.

8. The process for producing an organic curing agent containinghydrosilyl groups according to the above item 6, wherein the compoundselected from thiazoles and phosphines is triphenylphosphine.

9. The process for producing an organic curing agent containinghydrosilyl groups according to the above item 6, wherein the olefin isselected from a group consisting of the following formulae (1) to (4):

     CH.sub.2 ═C(R.sup.1)--R.sup.2 --O!aR.sup.3            ( 1)

     CH.sub.2 ═C(R.sup.1)--R.sup.2 --C(═O)!aR.sup.4    ( 2)

     CH.sub.2 ═C(R.sup.1)!aR.sup.5                         ( 3)

     CH.sub.2 ═C (R.sup.1)--R.sup.2 --C(═O)--O!aR.sup.6 ( 4)

wherein R¹ represents a hydrogen atom or a methyl group; R² represents ahydrocarbon radical having 0 to 18 carbon atoms, which may contain atleast one ether linkage; each of R³, R⁴ and R⁶ represents a monovalentto tetravalent organic group having 1 to 30 carbon atoms; R⁵ representsa monovalent to tetravalent hydrocarbon radical having 1 to 50 carbonatoms; and a is an integer selected from 1 to 4.

10. The process for producing an organic curing agent containinghydrosilyl groups according to the above item 6 or 9, wherein thepolyvalent hydrogen organosilicon compound is a trimethylsilyl terminalpolymethylhydrosiloxane.

11. The process for producing an organic curing agent containinghydrosilyl groups according to the above item 6 or 9, wherein thepolyvalent hydrogen organosilicon compound is a polyvalent hydrogenpolyorganosiloxane of 500 or less molecular weight having 3 or morehydrosilyl groups in 1 molecule.

12. The process for producing an organic curing agent containinghydrosilyl groups according to any one of the above items 6, 9 and 11,wherein the olefin is 1,9-decadiene and the polyvalent hydrogenorganosilicon compound is 1,3,5,7-tetramethylcyclotetrasiloxane.

13. The process for producing an organic curing agent containinghydrosilyl groups according to any one of the above items 6 to 12,wherein a compound selected from thiazoles and phosphines is added aftercompletion of the addition reaction of hydrosilyl groups to olefin usinga metal catalyst.

14. The process for producing an organic curing agent according to theabove item 6, wherein the hydrosilylation reaction is carried out in theabsence of solvent.

That is, a first aspect of the present invention is the method disclosedin each of the aforementioned items 1 to 5 in which the additionreaction of hydrosilyl (Si-H) groups to olefin using a metal catalyst iscontrolled by allowing a compound selected from thiazoles and phosphinesto coexist in the reaction system.

A second aspect of the present invention is the process for theproduction of an organic curing agent containing hydrosilyl groups,disclosed in each of the aforementioned items 6 to 14, which ischaracterized in that hydrosilylation of olefin and a polyvalenthydrogen organosilicon compound is carried out using the method of thefirst aspect of the present invention under such conditions thathydrosilyl groups remain in the formed material after the reaction,particularly in that the reaction is controlled by the method ofaforementioned item 5 and the aforementioned polyvalent hydrogenorganosilicon compound is used as the hydrosilyl group-containingcompound.

The term "to control the reaction" as used herein means, for example, toinhibit occurrence of sudden reaction in hydrosilylation reaction usinga metal catalyst, thereby preventing side reactions such as hydrolysisof hydrosilyl groups, disproportionation and polymerization ofpolysiloxane and the like and, when hydrosilyl groups are allowed toremain in product molecules, preventing reduction of the number ofremaining hydrosilyl groups caused by these side reactions.

The thiazoles to be used in the hydrosilylation method are notparticularly limited, but benzothiazole may be used preferably. Thephosphines are also not particularly limited, but triphenylphosphine maybe preferable.

There is no particular limitation on the amount of the aforementionedthiazoles and phosphines (also to be referred to as "additives"hereinafter) to be added to control the aforementioned reaction of thehydrosilylation method of the present invention. The amount of theadditives varies due to kind, amount, concentration and the like of eacholefin, hydrosilyl group-containing compound and catalyst, and dependson the desired degree of the reaction repression. Amount of theadditives if too large would entail considerably slow reaction, and iftoo small would not bear sufficient effect. In general cases, it may bepreferably from about 1 to 1,000 moles, more preferably from about 5 to50 moles, per 1 mole of the catalyst.

Though not particularly limited, examples of metal complexes to be usedas the catalyst include a platinum catalyst, a rhodium catalyst (e.g.,RhCl(PPh₃)₃ or RhAl₂ O₃), a ruthenium catalyst (e.g., RuCl₃), an iridiumcatalyst (e.g., IrCl₃), an iron catalyst (e.g., FeCl₃), an aluminumcatalyst (e.g., AlCl₃), a palladium catalyst (e.g., PdCl₂.2H₂ O), anickel catalyst (e.g., NiCl₂), a titanium catalyst (e.g., TiCl₄) and thelike, of which a platinum catalyst is preferred.

The platinum catalyst useful in the present invention is selected fromplatinum metal on a carrier, platinum compounds and platinum complexes.Examples of platinum compounds and platinum complexes includechloroplatinic acid, chloroplatinic acid hexahydrate, a complex ofchloroplatinic acid with an alcohol, aldehyde, ketone or the like, aplatinum-olefin complex (e.g., Pt(CH₂ ═CH₂)₂ Cl₂), aplatinum-vinylsiloxane complex (e.g., Pt_(n) (ViMe₂ SiOSiMe₂ Vi)_(m) orPt (MeViSiO)₄ !_(m)) (wherein Me represents a methyl group, Virepresents a vinyl group, and m and n are integers), dicarbonyldichloroplatinum and the like. Also useful are the platinum-hydrocarboncomplexes disclosed by Ashby in U.S. Pat. Nos. 3,159,601 and 3,159,662and the platinum-alcoholate catalyst disclosed by Lamoreaux in U.S. Pat.No. 3,220,972. The platinum chloride-olefin complex disclosed by Modicin U.S. Pat. No. 3,516,946 is also useful in the present invention.

Platinum metal is adhered on a carrier such as charcoal, alumina,zirconia or the like. Also useful in the present invention is aplatinum-containing material which catalyzes reaction between siliconhydride and the unsaturated moiety of an unsaturated compound. Thoughnot particularly limited, the catalyst may be used preferably in anamount of from 1×10⁻¹ to 1×10⁻⁸ mol per 1 mol of carbon-carbon doublebond. More preferably, it may be within the range of from 1×10⁻³ to1×10⁻⁷ mol.

The olefin to be used in the hydrosilylation reaction means a compoundhaving at least one carbon-carbon double bond capable of undergoinghydrosilylation and is not limited to C_(n) H₂, (n is an integer of twoor more) but preferably a terminal olefin having a terminalcarbon-carbon double bond.

Illustrative examples of olefin include linear alkenyl compounds such aspropylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-deceneand the like; diene compounds such as 1,5-hexadiene, 1,9-decadiene,4-vinylcyclohexane and the like; styrene compounds such as styrene,α-methylstyrone and the like; halogenized olefinic unsaturatedfunctional alkenyl compounds such as vinyl chloride, allyl bromide,allyl iodide, allylene bromide, tri- and tetrachloroethylene,tetrafluoroethylene, chloroprene, vinylidene chloride, dichlorostyreneand the like; oxygen-containing olefinic unsaturated functional alkenylcompounds such as allyl ether, vinyl ether, allyl alcohol, methyl vinylcarbinol, acrylic acid, methacrylic acid, vinyl acetic acid, oleic acid,linolenic acid, vinyl acetate, allyl acetate, butenyl acetate, allylstearate, methacrylate, ethyl crotonate, diallyl succinate, diallylphthalate and the like; nitrogen-containing olefinic unsaturatedfunctional alkenyl compounds such as indigo, indole, acrylonitrile,allyl cyanide and the like; unsaturated silicon compounds such asvinyltrimethylsilane, allyltrimethylsilane and the like; conjugate dienepolymers such as polyisoprene, polybutadiene and the like; olefinterminal polymers such as olefin terminal polypropylene glycol, olefinterminal hydrogenated polyisoprene, olefin terminal polyisobutylene,olefin terminal polyester, olefin terminal polycarbonate and the like;and alkenyl group-containing organopolysiloxane and the like.

In the production of organic curing agent containing hydrosilyl groupsin accordance with the process of the present invention, particularlypreferred olefin is an organic compound selected from a group consistingof the following formulae (1) to (4):

     CH.sub.2 ═C(R.sup.1)--R.sup.2 --O!aR.sup.3            ( 1)

     CH.sub.2 ═C(R.sup.1)--R.sup.2 --C(═O)!aR.sup.4    ( 2)

     CH.sub.2 ═C(R.sup.1)!aR.sup.5                         ( 3)

     CH.sub.2 ═C(R.sup.1)--R.sup.2 --C(═O)--O!aR.sup.6 ( 4)

wherein R¹ represents a hydrogen atom or a methyl group; R² represents ahydrocarbon radical having 0 to 18 carbon atoms, which may contain atleast one ether linkage; each of R³, R⁴ and R⁶ represents a monovalentto tetravalent organic group having 1 to 30 carbon atoms; R⁵ representsa monovalent to tetravalent hydrocarbon radical having 1 to 50 carbonatoms; and a is an integer selected from 1 to 4.

The hydrosilyl group-containing compound to be used in thehydrosilylation method of the present invention or the organic curingagent production process of the present invention is not particularlylimited, with the proviso that it can be used in the hydrosilylationreaction, and its examples include compounds represented by thefollowing formulae (5) to (7). In this instance, when used in theprocess of the production of the organic curing agent in the presentinvention, the hydrosilyl group-containing compound is a polyvalenthydrogen organosilicon compound, namely a compound which contains atleast 2 hydrosilyl groups in one molecule, in other words, a compoundwhich has at least 2 silicon atom-binding hydrogen atoms.

The silicon atom-binding hydrogen atoms may be located on the same Siatom or different Si atoms in the polyvalent hydrogen organosiliconcompound molecule. ##STR1##

(In the above formula, R⁷ to R¹³ are the same or different from oneanother and each represents a substituted or unsubstituted alkyl group,a substituted or unsubstituted cycloalkyl group or a substituted orunsubstituted aryl group; X represents a hydrogen atom or a substitutedor unsubstituted alkyl group, a substituted or unsubstituted cycloalkylgroup or a substituted or unsubstituted aryl group; m is an integer ofm>0 when X is a hydrogen atom or an integer of m≧1 when X is not ahydrogen atom; and n is an integer of n ≧0. In the organic curing agentproduction process of the present invention, m is an integer of m≧2.)##STR2##

(In the above formula, R¹⁴ to R¹⁶ are the same or different from oneanother and each represents a substituted or unsubstituted alkyl group,a substituted or unsubstituted cycloalkyl group or a substituted orunsubstituted aryl group; and p≧1, q≧0 and p+q≧3. In the organic curingagent production process of the present invention, p≧2.) ##STR3##

(In the above formula, R¹⁷ and R¹⁸ are the same or different from eachother and each represents a substituted or unsubstituted alkyl group, asubstituted or unsubstituted cycloalkyl group or a substituted orunsubstituted aryl group and r is an integer of 0 to 3.)

Illustrative examples of the hydrosilyl group-containing compoundinclude trimethylsilane, dimethylphenylsilane, dimethylsilane,methyldimethoxysilane, triethylsilane, triethoxysilane, trichlorosilane,methyldichlorosilane, dimethylchlorosilane, trimethoxysilane,tripropoxysilane, tributoxysilane, ethyldimethoxysilane,methyldiethoxysilane, dimethylmethoxysilane, dimethylethoxysilane,ethyldiethoxysilane, 1,1,3,3-tetramethyldisiloxane,1,1,1,3,5,5,5-heptamethyltrisiloxane, terminal trimethylsilylgroup-sealed methyl hydrogen siloxane polymer (H oil),dimethylsiloxane/methyl hydrogen siloxane copolymer,1,3,5-trimethylcyclotrisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxaneand the like.

Examples of the polyvalent hydrogen organosilicon compound to be used inthe organic curing agent production process of the present inventioninclude 1,1,3,3-tetramethyldisiloxane,1,1,3,3,5,5-hexamethyltrisiloxane, terminal trimethylsilyl group-sealedmethyl hydrogen siloxane polymer (also called H oil),dimethylsiloxane/methyl hydrogen siloxane copolymer,1,3,5-trimethylcyclotrisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxaneand the like.

Of these, a polyvalent hydrogen polyorganosiloxane of 500 or less inmolecular weight having 3 or more hydrosilyl groups in 1 molecule isparticularly preferred.

The hydrosilylation reaction of the hydrosilylation method of thepresent invention is carried out at a temperature of generally from 0°to 150° C., but preferably from 60° to 90° C. in order to make easycontrol in preventing undesirable side reactions.

In the organic curing agent production process of the present invention,an olefin compound and a polyvalent hydrogen organosilicon compound areused in such a manner that the organic curing agent produced by thehydrosilylation method of the present invention generally contains atleast 2 hydrosilyl groups. Though combination of the olefin andpolyvalent hydrogen organosilicon compound is not particularly limited,it may generally be divided roughly into two cases. That is, a case inwhich the olefin has only one carbon-carbon double bond in one moleculeand another case in which it has a plurality of carbon-carbondouble-bonds.

In the case of a single carbon-carbon double bond, combination of olefinand hydrosilyl group-containing compounds has a large degree of freedombecause of no cross-linking by olefin molecules, and their ratio can bechanged optionally under such conditions that the produced organiccuring agent contains 2 or more hydrosilyl groups as described above. Anillustrative example of such a case is modification by thehydrosilylation reaction of trimethylsilyl group-terminalpolymethylhydrosiloxane (also called H oil) with α-olefin.

When olefin has a plurality of carbon-carbon double bonds, it isnecessary to take into consideration a possibility of causing gelationof the whole reaction system due to generation of cross-linking by theolefin. In that case, it is desirable to use a polyvalent hydrogenorganosilicon compound whose hydrosilyl groups are in excess of thenumber of the olefin carbon-carbon double bond. It is desirable alsothat excess polyvalent hydrogen organosilicon compound can be removedafter completion of the hydrosilylation reaction. This compound may havea molecular weight of preferably 500 or less when it is removed from theformed organic curing agent by distillation.

When a catalyst remains in the product of the organic curing agentproduction process of the present invention, namely in an organic curingagent, various side reactions which cause problems in the course of thereaction of interest progress gradually even during storage of theproduct, thus causing deterioration of its storage stability in somecases. In the additives-added system of the present invention, such sidereactions can be prevented and the storage stability can be improvedwhen additives also remain in the product, but it is desirable to addanother compound selected from phosphines and thiazoles in order toreduce the catalytic activity quickly after completion of the reactionand to ensure further stabilization of the product during itsafter-treatment and storage. When the amount of such an additionalcompound is too large, use of the product containing residual additivesas a curing agent may adversely affect the curing reaction. Conversely,its amount if too small would bear no sufficient effect. In generalcases, it may be used in an amount of from 1 to 1,000 moles, preferablyfrom 5 to 50 moles, per catalyst.

In the hydrosilylation reaction of the organic curing agent productionprocess of the present invention, a solvent such as n-pentane, n-hexane,n-heptane, benzene, toluene, xylene or the like or a plasticizer such asprocess oil or the like may be used depending on the necessity tocontrol reaction temperature, viscosity of the reaction system and thelike, but the reaction may be carried out preferably under solvent-freeconditions, because it is desirable to obtain a material, generally apolyvalent hydrogen organosilicon compound, without purification whenthe material is recovered and recycled. Even under such solvent-freeconditions, an extremely small amount of solvent may be used at the timeof the addition of a catalyst and additives for the sake of theirdispersibility and easy handling. Though not particularly limited,examples of the solvent for use in such a purpose include xylene,toluene, benzene and the like. Such a solvent may be used in an amountof preferably 1% or less of the total reaction solution volume, morepreferably 0.1% or less when the recycle is frequent.

Method for the recovery of excess materials after completion of thereaction is not particularly limited, but it is desirable to carry outsimple distillation under a reduced pressure in view of the preventionof modification caused by excess heating of the product and materials tobe recovered and of easy handling, more preferably to use a thin filmdistillation apparatus from the viewpoint of short heating time and highthroughput speed.

Operation for the recovery and recycle of the materials has noparticular limitation. That is, corresponding amounts of consumedmaterials may be supplemented or only recovered materials may becollected and recycled.

There is no particular limitation about the apparatus for use in thepractice of the hydrosilylation reaction of the present invention, butit is desirable to use a pressure vessel such as autoclave or the likewhen the reaction of olefin with a hydrosilyl group-containing compoundis carried out at a temperature equal to or higher than the boilingpoint of the solvent used. In addition, it is desirable to use anapparatus having sufficient agitation capacity for the purpose ofeffecting homogeneous reaction.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a graph showing an example of changes with time of theformation reaction of a hydrosilyl group-containing curing agent.

BEST MODE OF CARRYING OUT THE INVENTION

Examples of the present invention are given below by way of illustrationand not by way of limitation.

Production Example 1:

A terminal allyl etherificated polyoxypropylene having a terminalcarbon-carbon double bond was synthesized in accordance with the methoddisclosed in JP-A-53-134095. Polyoxypropylene glycol having an averagemolecular weight of 3,000 was mixed with sodium hydroxide powder at 60°C., and the reaction was carried out by adding bromochloromethane toincrease the molecular weight. Next, thereto was added allyl chloride toeffect terminal allyl etherification at 110° C. Thereafter, the mixturewas treated with aluminum silicate to obtain purified terminal allyletherificated polyoxypropylene. Average molecular weight of thispolyether was about 8,000, and its allyl group content calculated fromits iodine value was 0.023 mol/100 g. Its viscosity was 135 poise (40°C.) when measured by an E-type viscometer.

Inventive Example 1:

To 200 g of the terminal allyl etherificated polyoxypropylenesynthesized in Production Example 1 were added 4.84 g of theorganopolysiloxane-based curing agent (allyl and Si-H groups areequivalent) synthesized in Inventive Example 3 and 5.61×10⁻⁴ mmol of Pt{CH₂ ═CH)Me₂ Si}₂ O!₂ catalyst solution, followed by thorough mixing tobe used as a master batch.

A 4 g portion of the batch was mixed with 7.6 mg of benzothiazole (1 wt% solution in toluene) (1 mole per platinum) and thoroughly kneaded. Aportion of the mixture was put on a gelation testing apparatus(manufactured by Nisshin Kagaku) to measure a snap up time (time untilit showed rubber elasticity) at a predetermined temperature.

In the same manner, respective snap up times were measured whenbenzothiazole was added in an amount of 10, 20 or 100 moles perplatinum.

Inventive Example 2:

The test of Inventive Example 1 was repeated except thattriphenylphosphine was used instead of benzothiazole. In this case,triphenylphosphine was used in an amount of 1, 1.5 or 3 moles perplatinum.

Comparative Examples 1 to 5:

The test of Inventive Example 1 was repeated except that tributylamine,phenyl sulfide, N,N-dimethylacetamide, pyridine or o-nitroanisole wasused instead of benzothiazole.

Table 1 shows results of the analysis of the products obtained inInventive Examples 1 and 2 and Comparative

Examples 1 to 5.

It is evident from these results that the reaction rate can becontrolled by the amount of added benzothiazole or triphenylphosphine.

                  TABLE 1                                                         ______________________________________                                                  Amount in Mole                                                      Additives   1     1.5    3   10    20   50    100                             ______________________________________                                        Inventive Examples                                                            1           6.0   --     --  34.3  270.0                                                                              *     --                              2           9.7   133.0  *   --    --   --    --                              Comparative Examples                                                          1           3.3   --     --  6.7   --   9.0   --                              2           3.0   --     --  4.3   --   5.7   --                              3           5.0   --     --  4.7   --   4.0   --                              4           6.7   --     --  14.3  --   23.3  28.3                            5           3.7   --     --  3.7   --   4.7   --                              ______________________________________                                         (In Table 1, unit: seconds; *: no curing.)                               

Additives shown in Table 1 are as follows. Example 1, benzothiazole;Inventive Example 2, triphenyl phosphine; Comparative Example 1,tributylamine; Comparative Example 2, phenyl sulfide; ComparativeExample 3, N,N-dimethylacetamide; Comparative Example 4, pyridine; andComparative Example 5, o-nitroanisole.

Inventive Example 3:

A 50 liter capacity stainless steel reaction vessel equipped with anagitator was charged with 10.0 kg (41.6 mol) of1,3,5,7-tetramethylcyclotetrasiloxane and 12.0 kg of toluene and themixture was heated at 80° C. in an atmosphere n. With thoroughagitation, 189 mg (1.40 mmol) of benzothiazole as a 1 wt % toluenesolution was added thereto. Ten minutes thereafter, abis(1,3-divinyl-1,1,3,3-tetramethyldisiloxane)-platinum complex catalyst(8.2×10⁻² mmol) was further added. After additional 10 minutes, amixture of 0.575 kg (4.16 mol) of 1,9-decadiene and 1.15 kg of toluenewas added spending 1 hour while loading sufficient agitation. Afteraddition of the entire amount, the agitation was continued at 80° C.until disappearance of remaining 1,9-decadiene which was determined by agas chromatography. The reaction mixture was concentrated to give 2.15kg of an Si-H group-containing curing agent as the resulting residue. AGPC analysis revealed that the main component of this product is acompound (a) having a structure of the following formula. Also,determination of the amount of hydrogen gas generated by hydrolysis ofthis product with an aqueous alkali solution revealed that the Si-Hgroup content of this product is 0.951 mol/100 g. During this reaction,exothermic reaction was hardly observed. Results of the analysis of therate of this reaction calculated based on the remaining amount of1,9-decadiene are shown in FIG. 1. In this drawing, C representsconcentration of remaining 1,9-decadiene and C₀ represents its initialconcentration. It can be seen that the reaction rate is stable andalmost first-order with respect to 1,9-decadiene. The product showed nosignificant changes in its properties after a half year of storage atroom temperature. ##STR4## Inventive Example 4:

To the reaction system practiced in the same manner as described inInventive Example 3 was added, after completion of the reaction, 189 mg(1.40 mmol) of benzothiazole as a 1 wt % toluene solution. Thereafter,the reaction mixture was concentrated in the same manner. The productshowed no significant changes in its properties after 2 months of sealedstorage at 40° C.

Inventive Example 5:

A 5 liter capacity glass reaction vessel equipped with an agitator wascharged with 63.3 g (Si-H 1.00 mol) of H-oil (trimethylsilyl sealedpolymethylhydrosiloxane; Si-H 15.8 mmol/g) and 60.0 ml of toluene, andthe mixture was heated at 80° C. in an atmosphere of nitrogen. Withthorough agitation, 2.99 mg (2.21×10⁻⁵ mmol) of benzothiazole as a 1 wt% toluene solution was added. Ten minutes thereafter, abis(1,3-divinyl-1,1,3,3-tetramethyldisiloxane)-platinum complex catalyst(0.52×10⁻⁵ mmol) was further added. After additional 10 minutes, amixture of 26.0 g (0.25 mol) of styrene and 20.0 ml of toluene was addedspending 30 minutes while loading sufficient agitation. After additionof the entire amount, the heating agitation was continued for 2 hours.The reaction mixture was concentrated to give 83.3 g of an Si-Hgroup-containing curing agent as the resulting residue. Theaforementioned analysis revealed that the Si-H group content of thisproduct is 0.78 mol/100 g. This product showed no significant changes inits properties after 1 month of storage at room temperature.

Inventive Example 6:

An Si-H group-containing curing agent was synthesized in the same manneras described in Inventive Example 5 except that styrene was used in anamount of 52.0 g and added neat spending 1 hour. The Si-H group contentwas found to be 0.40 mol/100 g. This product showed no significantchanges in its properties after 1 month of storage at room temperature.

Comparative Example 6:

An Si-H group-containing curing agent was synthesized in the same manneras described in Inventive Example 5 except that benzothiazole was notadded. The Si-H group content was found to be 0.50 mol/100 g. Thisproduct gelatinized after 1 week of storage at room temperature.

Reference Example 1:

To 200 g of the terminal allyl etherificated polyoxypropylenesynthesized in Production Example 1 were added 4.84 g of theorganopolysiloxane-based curing agent synthesized in Inventive Example 2(allyl and Si-H groups are equivalent), 0.20 g (1.38 mmol) of dimethylmaleate and 2.3×10⁻² mmol of Pt {CH₂ ═CH)Me₂ Si}₂ O!₂ catalyst solution,followed by thorough mixing. The thus prepared composition was pouredinto a mould of about 2 mm in thickness and subjected to 1 hour ofdegassing at room temperature in a vacuum dryer. Thereafter, this washeated at 100° C. for 1 hour to give a cured product. A No.3 dumbbelltest piece was prepared by punching the thus cured sheet in accordancewith JIS K 6301 and subjected to a tensile test at an elastic stressrate of 200 mm/minute. Results of the analysis are shown in Table 2.

                  TABLE 2                                                         ______________________________________                                                                                       Gel                                 M25    M30     M50  M100  M150 TB    EB   Content                        ______________________________________                                        Inv  1.55   1.88    3.3  5.12  6.63 8.64  217% 92%                            Ex. 6                                                                         ______________________________________                                    

In Table 2, M (the succeeding numeral indicates elongation expressed by%) represents modulus (unit: kg/cm²). TB represents breaking strength(kg/cm²) and EB represents elongation at rupture. The term "gel content"means decreasing ratio of weight of the cured product when it was putinto a wire netting, soaked for 1 day in toluene and then dried.

Inventive Example 7:

A 50 liter capacity stainless steel reaction vessel equipped with anagitator was charged with 44.25 kg (184.0 mol) of fresh1,3,5,7-tetramethylcyclotetrasiloxane and heated at 80° C. in anatmosphere of nitrogen. With thorough agitation, thereto was added asolution of 248 mg (1.84 mmol) of benzothiazole dissolved in 2.0 g oftoluene. Ten minutes thereafter, xylene solution of abis(1,3-divinyl-1,1,3,3-tetramethyldisiloxane)-platinum complex catalyst(1.11 g; 1.08×10⁻¹ mmol) was further added. After additional 10 minutes,a mixture consisting of 2.874 kg (20.8 mol) of 1,9-decadiene and 5.75 kg(23.9 mol) of fresh 1,3,5,7-tetramethylcyclotetrasiloxane was addedspending 1 hour while loading sufficient agitation. After addition ofthe entire amount, the agitation was continued at 80° C. untildisappearance of remaining 1,9-decadiene which was determined by a gaschromatography. After completion of the reaction, thereto was added asolution of 248 mg (1.84 mmol) of benzothiazole dissolved in 2.0 g oftoluene. The reaction mixture was concentrated by evaporation under areduced pressure at about 60° C. to obtain 10.8 kg of a colorless andtransparent Si-H group-containing curing agent as the resulting residue.This yield means that about 16% of the material1,3,5,7-tetramethylcyclotetrasiloxane was consumed and about 84% wasrecovered. A GPC analysis revealed that the main component of thisproduct is the compound (a) described in Inventive Example 3. Also,determination of the amount of hydrogen gas generated by hydrolysis ofthis product with an aqueous alkali solution revealed that the Si-Hgroup content of this product is 0.976 mol/100 g. During this reaction,exothermic reaction was hardly observed. This product showed nosignificant changes in its properties after 2 months of storage at 40°C. Analyses of the recovered material by gas chromatography and ¹ H-NMRshowed that modification did not occur and highly purified material wasrecovered.

The same production process was repeated several times. The same productwas obtained with no problems and highly purified material wasrecovered.

Inventive Example 8:

When the synthesis of Inventive Example 7 was repeated using1,3,5,7-tetramethylcyclotetrasiloxane recovered in Inventive Example 1,the same product of Inventive Example 7 was obtained and highly purifiedmaterial was recovered.

The same production process was repeated several times. The same productof Inventive Example 7 was obtained with no problems and highly purifiedmaterial was recovered.

Inventive Examples 9 to 16:

The recovery and recycling of a material1,3,5,7-tetramethylcyclotetrasiloxane were repeated in the same manneras described in Inventive Example 8 until the material was used 10times. The 1,3,5,7-tetramethylcyclotetrasiloxane was used as the onlymaterial in each synthesis. The same product of Inventive Example 7 wasobtained in each recycled use with no problems, and the recoveredmaterial showed no modification and its high purity was maintained,though accumulation of a small amount of impurities was observed as therecycle numbers increased. Since recovery of the material was carriedout by simple distillation, recovery loss was hardly found and 80% ormore of the material was converted into the product after 10 times ofthe use of the material.

Results of the analysis of products obtained in Inventive Examples 7 to16 are shown in Table 3.

                  TABLE 3                                                         ______________________________________                                        Inventive                                                                              Number of Times                                                                            Yield  Si--H Value of                                   Examples of Material Used                                                                           (kg)   Material (mol/100 g)                             ______________________________________                                         7       1            10.7   0.976                                             8       2            10.6   0.980                                             9       3            10.5   0.993                                            10       4            10.8   0.986                                            11       5            10.7   0.984                                            12       6            10.8   0.967                                            13       7            10.8   0.982                                            14       8            10.7   0.968                                            15       9            10.6   0.973                                            16       10           10.8   0.975                                            ______________________________________                                    

INDUSTRIAL APPLICABILITY

The present invention provides a method for easy control ofhydrosilylation reaction and a process for the production of an organiccompound modifying silicon compound having 2 or more hydrosilyl groupsin the molecule making use of the controlling method. This compound isused as a curing agent of addition type curable compositions. As anaccompanying effect, storage stability of the produced curing agent isimproved when a catalyst and additives of the present invention remaintherein, in comparison with the case in which only the catalyst remains.

We claim:
 1. A process for producing an organic curing agent containinghydrosilyl groups using a hydrosilylation reaction, which comprisescarrying out hydrosilylation of, an olefin by reacting said olefin witha polyvalent hydrogen organosilicon compound using a metal catalyst inthe presence of a compound selected from thiazoles and phosphines tocontrol the hydrosilylation reaction, wherein the hydrosilyl groups arepresent in excess of the number of olefin carbon-carbon double bonds. 2.The process for producing an organic curing agent containing hydrosilylgroups according to claim 1, wherein said compound selected fromthiazoles and phosphines is benzothiazole.
 3. The process for producingan organic curing agent containing hydrosilyl groups according to claim1, wherein said compound selected from thiazoles and phosphines istriphenylphosphine.
 4. The process for producing an organic curing agentcontaining hydrosilyl groups according to claim 1, wherein said olefinis selected from a group consisting of the following formulae (1) to(4):

     CH.sub.2 ═C(R.sup.1)--R.sup.2 --O!aR.sup.3            ( 1)

     CH.sub.2 ═C(R.sup.1)--R.sup.2 --C(═O)!aR.sup.4    ( 2)

     CH.sub.2 ═C(R.sup.1)!aR.sup.5                         ( 3)

     CH.sub.2 ═C(R.sup.1)--R.sup.2 --C(═O)--O!aR.sup.6 ( 4)

wherein R¹ represents a hydrogen atom or a methyl group; R² represents ahydrocarbon radical having 0 to 18 carbon atoms, which may contain atleast one ether linkage; each of R³, R⁴ and R⁶ represents a monovalentto tetravalent organic group having 1 to 30 carbon atoms; R⁵ representsa monovalent to tetravalent hydrocarbon radical having 1 to 50 carbonatoms; and a is an integer selected from 1 to
 4. 5. The process forproducing an organic curing agent containing hydrosilyl groups accordingto claim 1 or 4, wherein said polyvalent hydrogen organosilicon compoundis a trimethylsilyl terminal polymethylhydrosiloxane.
 6. The process forproducing an organic curing agent containing hydrosilyl groups accordingto claim 1 or 4, wherein said polyvalent hydrogen organosilicon compoundis a polyvalent hydrogen polyorganosiloxane of 500 or less in molecularweight having 3 or more hydrosilyl groups in 1 molecule.
 7. The processfor producing an organic curing agent containing hydrosilyl groupsaccording to claim 1 or 6, wherein said olefin is 1,9-decadiene and saidpolyvalent hydrogen organosilicon compound is1,3,5,7-tetramethylcyclotetrasiloxane.
 8. The process for producing anorganic curing agent containing hydrosilyl groups according to claim 1or 4, wherein a compound selected from thiazoles and phosphines is addedafter completion of the addition reaction of hydrosilyl groups to olefinusing a metal catalyst.
 9. The process for producing an organic curingagent according to claim 1, wherein said hydrosilylation reaction iscarried out in the absence of solvent.